The theme of this Program Project Grant is heavily based around the use of preclinical in vivo models to study the molecular mechanisms involved with the effects to cancer on the skeleton. Each project requires the use of animal models and careful assessment and monitoring of those animals for both skeletal and soft tissue metastases. The Small Animal Core proposed here will provide support for all work involving animals within each individual project. Services will include maintenance of tumor cell lines, management of all procedures involving small animals as well as state-of-the art methods for assessing the effects of cancer on the skeleton. This core builds on the previously existing laboratory core by incorporating new techniques such as optical imaging of green fluorescent protein expressing tumor cells, MicroSPECT, MicroPET and microCT for the assessment of tumor effects of the skeleton and tumor burden. An additional strength of the Small Animal Core is the participation of recognized experts in these areas. Techniques such as MicroSPECT, Micro PET and MicroCT are used in clinical diagnostics for patients with both breast cancer and multiple myeloma but to our knowledge have not yet been utilized in small animal models of metastatic disease. Use of these techniques will allow us to make direct comparisons between our preclinical models and disease in patients providing for validation of our preclinical models of breast cancer and multiple myeloma. Furthermore, these techniques will build on those that we have used in the past such as radiography and histomorphometry by allowing us to obtain a much more thorough picture of tumor burden and distribution in the whole intact animal, while providing much better resolution.